1. Field of the Invention
In one aspect, this invention relates to vacuum control valves. In a further aspect, this invention relates to servo-controlled vacuum programmers.
2. Prior Art
Linear vacuum programmers or diverters are known in the art. One example is shown in U.S. Pat. No. 3,983,930 issued to Rudolph J. Franz. This patent shows a linear diverter valve with an elongated body and a bore extending longitudinally therein. A plurality of ports are axially spaced along the body and are in fluid communication with the bore. A diverter valve assembly is mounted within the bore; the diverter valve has sealing means at each end which seal the bore. The diverter valve also has a reduced center section which allows fluid flow within the bore between the two sealing means. Therefore, any ports which lie between the sealing means will be in fluid communication with each other. As the two sealing means are moved longitudinally along the bore, selected ports can be interconnected by means of the reduced portion of the valve.
A problem arises with the prior art devices in assembling the valve in a system. Where a plurality of devices are to be controlled by the programmer, a number of port-connecting nipples are placed on the valve body. The ports and nipples are placed in proximity and, therefore, the ports are spaced about the same distance apart as the nipples. This has created a problem in that the size of the programmer has been determined by the port spacing which in turn has been dictated by the size of the port-connecting nipples.